(mac_do_receive_drag): Drag-and-drop items are now
stored in member `args' of struct input_event.
(x_use_underline_position_properties): Undo 2005-07-13 change.
(syms_of_macterm) <x-use-underline-position-properties>: Likewise.
(mac_use_core_graphics, mac_wheel_button_is_mouse_2)
(mac_pass_command_to_system, mac_pass_control_to_system): New
boolean variables renamed from Lisp_Object ones
Vmac_use_core_graphics, Vmac_wheel_button_is_mouse_2,
Vmac_pass_command_to_system, and Vmac_pass_control_to_system. All
uses changed.
(syms_of_macterm): DEFVAR_BOOL them. Remove previous DEFVAR_LISPs.
Make them user options.
(mac_handle_command_event, mac_store_services_event): Call
create_apple_event_from_event_ref without 5th argument.
(backtranslate_modified_keycode): Mask off modifier keys that are
mapped to some Emacs modifiers before passing it to KeyTranslate.
(syms_of_macterm): Make variables `mac-emulate-three-button-mouse',
`mac-wheel-button-is-mouse-2', and `mac-*-modifier' user options.
Fix docstrings of `mac-*-modifier'.